Hitherto, as ah active ingredient having a PDE4 inhibitory effect, reports have been made about naphthalene derivatives each having a specific chemical structure. Known have also been medical compositions for preventing or treating asthma, therapeutic agents for dermatitis, and therapeutic agents for skin, injury that each make use of advantageous effects of any one of the derivatives (for example, Patent Literatures 1 to 4 listed below).
However, such an active ingredient is a drug that does not easily ensure the stability of a formulation thereof. As a solving solution for ensuring the uniformity or bleeding of the drug in an ointment, a method of increasing the hardness of the formulation is easily conceivable. In this case, however, a problem is caused that it s difficult to apply the ointment.